The present invention relates to a roll stand. More particularly this invention concerns a compact rod-rolling stand with two rolling lines.
In the hot-rolling of rod, typically immediately after it is cast as a billet or bloom, it is known to use a roll stand having a succession of pairs of rolls, vertical pairs alternating with horizontal pairs, that serve to reduce the cross-sectional size of the incoming workpiece to the desired small rod cross section.
With small calibers it is understood that the procedure is quite expensive, both because of the process time as well as due to its complexity. Thus in order to insure acceptable productivity, the rolling speed must always be increased, speeds of 100 m/sec being exceeded by far.
The solution is the split-roll procedure such as shown in Japanese 60-130,401. This produces two strands from a single incoming strip and passes each of the individual strands through a series of roll pairs, with each succeeding roll pair oriented 90xc2x0 offset from the preceding one. Similarly it is possible to expand this method and reduce a flat strip to four or more strands that are individually rolled. Thus, starting with a square-section bloom or billet some 160 mm on a side coming straight from the furnace, it is possible to produce rod at a rate of for example 37 ton/hour.
It is also possible to use horizontally arranged winding machines, for instance of the Edembor(trademark) type to produce rod or wire with a diameter smaller than 5.5 mm by means of several rolling lines.
Such use of multiple rolling lines greatly increases the complexity and also the overall size of the treatment plant.
It is therefore an object of the present invention to provide an improved dual-line rolling stand.
Another object is the provision of such an improved dual-line rolling stand which overcomes the above-given disadvantages, that is which is quite compact and of relatively simple and inexpensive construction.
A further object is to provide a roll stand which is particularly easy to service and repair.
A two-line roll stand has according to the invention a frame, an upper shaft on the frame, and two lower shafts on the frame spaced horizontally from each other below the upper shaft and centered on axes forming with an axis of the upper shaft an isosceles triangle. A plurality of identical drive units each have a pair of rolls and gearing connected to the respective rolls. The lower shafts each carry at least two of the drive units and the upper shaft carries at least four of the drive units. Respective bevel gears on the shafts are connected to the gearing of the drive units. The drive units of one of the lower shafts are tipped outward away from the drive units of the other lower shaft with the rollers of the lower-shaft drive units defining a pair of roll lines spaced below and symmetrically flanking the upper shaft. The upper-shaft drive units are tipped downward with the rollers of each upper-shaft drive unit aligned on the lines with the rolls of the respective lower-shaft drive units. A single motor has an output directly connected to drive gears on the shafts for synchronously rotating all the shafts and thereby rotating all the rolls via the respective bevel gears and the gearing of the respective drive units.
Thus this system uses identical drive units so as to simplify servicing the machine. Furthermore the use of three shafts oriented on a triangle with interleaved pairs of rolls makes the stand very compact, in particular longitudinally parallel to the roll lines.
According to the invention the lower shafts each carry the same predetermined number of the drive units and the upper shaft carries twice as many of the drive units. In one preferred embodiment each lower shaft carries three of the drive units and the upper shaft carries six of the drive units. The longitudinal spacing parallel to the lines between the upper-shaft drive units is half a longitudinal spacing between the lower-shaft drive units.
Furthermore in accordance with the invention seen in vertical section the axes of the shafts form with the lines a substantially equilateral pentagon.